Merge pull request #47 from dkj/devel

Mem leak fix
Changes update
Merge pull request #48 from wtsi-npg/devel

memory leak fix
Merge pull request #49 from wtsi-npg/master

pull from master to devel (tag 74.4 )
remove req for lims driver objects to have init_attrs method (to pass tests)
remove init_attrs
promote attribute _driver to driver